328 



REGENERATION AND NEOTENY 



later, and the error caused by this difference is very small. At 15°C. 

 in only one instance was the day of the first molting not recorded, 

 and the error in this instance may amount to from 1 to 4 days. 

 As the figures show, there was no difference between the controls and 

 the experimentals at 15°C., both series metamorphosing 243 days 



TABLE I. 

 Regeneration and Metamorphosis in Ambystotna opacuni. 



All four series fed on earthworms; A and E kept at approximately 25°C. aver- 

 age temperature, C and G approximately 15°C. average temperature. In E and 

 G, at 46 days after hatching, both fore limbs were cut oflE, and at 88 days 50 per 

 cent of the tails was cut oflf. 



after hatching. At 25°C. the difference was very small; the regen- 

 erating series metamorphosed only 16 days later than the controls. 

 These results show that in Amby stoma opacum neoteny cannot be 

 produced by removal of parts of the body and their regeneration. 

 Beyond this no conclusions can be safely drawn. It should be men- 

 tioned, however, that in all four series approximately the same amount 

 of food was available for the animals. The earthworms which served 

 as food were given in pieces of approximately the same size. Since, 

 however, the amount of food in these series was not large enough to 

 cover the demand of normal growth, the animals were partly starved, 

 as may be seen also from the length of the larval period, which amounts 



